1. Field of Invention
This invention relates to a blade or cutting block of a hair cutter or shaver. In particular, the present invention relates to a blade block structure and technique to reduce a cost of the blade block and to improve an efficiency of assembling the blade block of hair cutter.
2. Description of Related Art
Conventionally, as shown in FIGS. 15(a) and 15(b), a blade block Aa is constructed by mounting a movable blade 5 on a blade base 6 so as to reciprocate with respect to a fixed blade 4. The blade block Aa is detachably mounted onto a body of a hair cutter or shaver. The fixed blade 4 having a comb-like portion is brought into contact with the movable blade 5 via a spring 18, and a cover 20 fixes or secures the fixed blade 4 and the movable blade 5 to the blade base 6. A guide mechanism is provided to reciprocate the movable blade 5 with respect to the fixed blade 4 is constructed as follows. Guide members 21 project from the blade base 6, and are inserted into insertion holes 4a and 5a formed in the fixed blade 4 and the movable blade 5, respectively. A driving force is transmitted from a drive mechanism in the body of the hair cutter to the movable blade 5, so that the movable blade 5 reciprocates within the range of the elongated insertion hole 5a. 
Further, the movable blade 5 is pressed toward and against the fixed blade 4 by a spring portion, which is separate from the movable blade 5, and is mounted to the blade base 6.
The blade block Aa as described above is detachably mounted to the body of the hair cutter. In particular, in a medical hair cutter (such as is used e.g. to prepare a patient for a medical procedure by shaving the hair from a portion of the patient""s body), the blade block Aa, including the blade base 6, the fixed blade 4 and movable blade 5 and so on, which directly contact a human skin is disposable and is not used more than once, to ensure safety and sanitariness. Accordingly, it is desired to reduce a cost and to improve efficiency of assembling of the blade block Aa.
On the other hand, in the conventional blade block structure of the hair cutter, the number of parts is large and the process for assembling the blade block is inefficient.
Accordingly, the present invention is provided in view of the above-described problems. It is an objective of the present invention to provide a blade block of a hair cutter, in which the number of parts are reduced to improve the efficiency of assembly of the blade block of the hair cutter, and automated assembly can easily be achieved, and the cost can be reduced.
To achieve the above and/or other goals, the present invention provides a blade block of a hair cutter that is detachably mountable to a hair cutter body. The blade block includes a fixed blade and a movable blade that reciprocates with respect to the fixed blade. The blade block includes a blade unit, a blade base and a mounting unit. The blade unit includes the fixed blade and the movable blade coupled by a reciprocating guide that enables the movable blade to reciprocate with respect to the fixed blade. The blade base defines an insertion opening. The mounting unit enables the blade unit to be mounted to the blade base when the blade unit is inserted into the insertion opening, so that a cutting edge of the blade unit extends toward and is exposed to the outside or exterior of the blade block.
According to the construction described above, the fixed blade and the movable blade are assembled into the blade unit by using the reciprocating guide. The blade unit is inserted into the insertion opening of the blade base, and is fixed to the blade base by the mounting unit in a condition or orientation such that the cutting edge extends toward outside of the blade block. Thus, the number of parts can be reduced in comparison with the conventional construction, and assembling of the blade block can be automated. Thus, the cost of manufacturing the blade block can be reduced. In addition, since the reciprocating guide is provided between the fixed blade and the movable blade, where machining precision can easily be achieved, the precision of the reciprocating guide function of the movable blade can be easily improved, and sharpness of the blade unit is easily maintained.
Preferably, a skin contact surface is provided at an outer surface of the blade base, and the cutting edge of the blade unit, inserted into the insertion opening, is inclined with respect to the skin contact surface. According to and as a result of this structure and construction, even if the blade base has a certain thickness, the cutting edge is not separated from and can tightly and closely contact the skin. Thus, even hair that might otherwise easily escape from the cutting edge, such as downy hair, can be held and cut short.
Preferably, the blade base includes a base plate, a wall portion provided at a periphery of the base plate and a corner portion formed between the base plate and the wall portion. The insertion opening is provided in a vicinity of the corner portion. The blade base is slidably detachably mounted to the hair cutter body. According to this construction, since the blade unit is inserted into the insertion opening provided in the vicinity of the corner portion, the cutting edge can be closely applied to the skin. Further, since the blade base is slidably attached to and detached from the hair cutter body, the blade block can easily be attached and detached by using a single hand.
Further, at least one stopper to position the fixed blade with respect to the blade base can be provided at each opposite side edge of the fixed blade. According to this construction, the blade unit can be securely supported against a load or force in the lateral direction of the fixed blade, in other words, in the reciprocating direction of the movable blade. Thus, a mounting strength (i.e., structural rigidity) of the blade unit can be improved.
Further, it is preferable that the fixed blade includes at least one guide piece, preferably formed by cutting and bending, so as to enable the movable blade to reciprocate. According to this construction, for example, the guide piece can be formed at the same time that the fixed blade is manufactured (e.g. by pressed or stamped). Thus, the guide piece can be formed easily and with improved precision.
The guide piece can extend in parallel with a reciprocating direction of the movable blade, so that the guide piece guides the movable blade surface contact with the movable blade while the movable blade reciprocates. According to this construction, the guiding of the movable blade in the reciprocating direction is satisfactorily performed by the guide piece extending in parallel with the reciprocating movement direction of the movable blade. In addition, the strength of the blade block due to the thickness of the guide piece can suppress backlash in a direction toward the cutting edge. Thus, the guiding precision can be improved. Further, since the guide piece extends in parallel with the reciprocating movement direction of the movable blade, and a broken (cut) face of the guide piece does not contact the edge of the guide hole, the roughness of the broken (cut) face of the guide piece does not affect the guiding function.
Preferably, a plurality of guide pieces extend in parallel with each other and are spaced from each other in a direction perpendicular to the reciprocating movement direction of the movable blade. According to this structure, the strength of the guide pieces against the force toward the cutting edge can substantially double. In addition, since a plurality of guide pieces are provided in parallel with each other, each guide piece does not require high size precision. Thus, the size precision does not have to be manufactured with a high precision (i.e. to size tolerance is high).
Alternatively, the guide piece can extend in a direction perpendicular to the reciprocating movement direction of the movable blade. The opposite edges of the guide piece, in a width direction thereof, slidably contact facing edges spaced in the width direction of a guide hole provided in the movable blade. According to this construction, since the guide piece can be guided at opposite edges in the width direction, its strength in a direction toward the cutting edge can be sufficiently improved. Further, the strength to support the movable blade against loads or forces at the time of cutting hair can be improved, and backlash can be avoided.
Further, the movable blade can have a guide hole that is elongated in the reciprocating movement direction, and a widened opening at one end of the guide hole. A stopper portion is further provided at a tip of the guide piece. The stopper portion is smaller than the widened opening and is larger than a width of the guide hole. According to this construction, the stopper portion can be inserted into the guide hole through the widened portion. Thus, the fixed blade is prevented from separating from the movable blade, and thus, the blade unit is prevented from falling apart.
The reciprocating guide can include a guide hole provided in the movable blade, a guide piece projecting from the fixed blade and slidably movable with respect to the guide hole, and a bent portion provided at an edge of the guide hole. According to this construction, since the bent portion provided at an edge of the guide hole slidably contacts the guide piece, the guide piece does not contact and is not guided by a broken (cut) edge of the guide hole. Thus, the guiding function becomes stable and unusual noise is prevented from occurring.
The guide piece and the bent portion of the guide hole can extend in opposite directions so as to face each other. According to this construction, since the guide piece is guided by the bent portion, which faces and slidably contacts the guide piece, the height of the guide piece can be shortened, and thus, the thickness of the blade unit can be decreased. In addition, since the bent portion extends toward the guide piece, the blade base does not require a portion into which the bent portion extends.
Further, for example, when the facing bent portions, provided at the opposing edges of the guide hole, are bent by more than 90 degrees, a sharp taper can be provided toward the bent portion (i.e. the movable blade). Thus, the efficiency of assembling the blade block can be improved, when the opposing bent portions engage with the guide pieces, which face the bent portions.
Alternatively, the guide piece and the bent portion of the guide hole can extend in a same direction. According to this structure, an introducing area for the guide piece can be formed naturally and simultaneously with a bent surface formed at the bent portion of the guide hole.
In addition, when the bending angle of the facing bent portions are less than 90 degrees, an amount of press fitting (bending) of the facing guide pieces can be set (or adjusted) to obtain a predetermined guiding function. Accordingly, the guide piece and the guide hole do not require high precision in their size and enable manufacturing with large tolerances.
It is preferable to further include an insertion guide portion provided on the blade base. The insertion guide portion guides the blade unit when the blade unit is assembled to the blade base by insertion of the blade unit into the insertion opening of the blade base. According to this construction, a positioning operation of the blade unit can be easily performed by the insertion guide portion formed on the blade base. Thus, efficiency of assembling of the blade unit can be improved.
It is preferable to further include a spring provided in the blade unit and an introducing portion provided on the blade base to introduce the spring to the blade base. According to this construction, when the blade unit is assembled with the blade base, the spring is prevented from deformation, which might occur when the spring is hooked by the blade base. On the contrary, the blade base is prevented from being scraped by the spring. Thus, the predetermined set pressing force of the spring is not changed, the assembling can be stable (i.e. not prone to error), and the movable blade can be stably pressed toward the fixed blade.
Preferably, the spring includes a flat portion, and corners of a peripheral surface of the spring are rounded or beveled. According to this structure, when the blade unit is inserted into the insertion opening of the blade base so as to be assembled with each other, the spring is easily slidable at the flat portion. Thus, the blade unit can be easily assembled to the blade base. In addition, since the corners of the peripheral surface of the spring are rounded or beveled, the spring is prevented from deformation, which might occur when the spring is hooked by the blade base. On the contrary, the blade base is prevented from being scraped by the spring. Thus, the predetermined or preset pressing force of the spring is not changed, the assembling can be stable, and the movable blade is stably pressed toward the fixed blade. Further, even when the spring is unitarily formed with the movable blade as one piece or connected with the movable blade, i.e., when the movable blade and the spring move together, the spring does not scrape the blade base and is not hooked by the blade base. Thus, driving of the movable blade can be made stable.
According to another aspect of the present invention, a blade block of a hair cutter includes a fixed blade and a movable blade which reciprocates with respect to the fixed blade. The blade block which is detachably mounted to a hair cutter body, is provided with a reciprocating guide including at least one guide piece projecting from the fixed blade, and at least one guide hole provided in the movable blade. The at least one guide piece is inserted into the at least one guide hole so that the movable blade can reciprocate within the range defined by the reciprocating hole. According to this construction, the guide piece can be unitarily formed with the fixed blade as one piece. Thus, the construction of the reciprocating guide can be simplified.